Field standards for hybrid corn seed certification are:

(1) Hybrid corn seed isolation:

(a) A specific hybrid must be located so that the seed parent is not less than six hundred and sixty feet from corn of a different color or texture with the following exceptions:

(i) Hybrid seed production fields of dent sterile popcorn need not be isolated from yellow dent field corn; or

(ii) When the contaminating corn is of a different color or texture aggregating less than one-fourth acre on one exposure, the isolation distance may be modified in accordance with the table listed in this section.

(2) A specific hybrid corn must be located so that the seed parent is not less than four hundred and fifteen feet from other corn of the same color or texture. The planting of pollen parent border rows and the size of the crossing field according to the following table may modify this distance.

(a) The border rows and pollen parent rows must be planted with certified first generation seedstock, must be shedding pollen simultaneously with silk emergence of the seed parent and must not be separated from the seed parent by more than thirty-three feet.

(b) A field planted with the same eligible pollen parent may be used as an isolation buffer if it is applied for certification, inspected and meets field requirements for certification.

(c) Full credit is not given where poor stands of border corn exist, where the border rows have been detasseled, or where, for any reason, the border rows are not shedding pollen as plentifully as the pollen parent rows. Because of the difficulty of obtaining and maintaining a good stand of corn, the planting of more than the minimum number of border rows is recommended.

(d) The maximum distance a seed parent row shall be from a pollen parent row is fifteen feet.

(3) Corrections for improper isolation of hybrid corn must be made by one of the following methods:

(a) By completely destroying or by detasseling the necessary contaminating corn before silks appear in the seed parent in the field to be certified; or

(b) By completely destroying the seed producing plants that are improperly isolated from contaminating corn before the final field inspection.

(4) Hybrid corn detasseling or pollen control. More than five percent of the stalks of the seed parent must have apparently receptive silks for the following provisions to apply. Apparently receptive silks are emerged silks which are not wilted or brown.

(a) An isolation is not accepted for certification if upon inspection by the certifying agency more than one percent of the stalks of the seed parent have shed pollen, or if the total number having shed pollen on any three days of inspection exceeds two percent.

(b) When more than one combination of hybrid corn is grown in the same isolation and the seed parent of one or more is shedding pollen in excess of one percent, all seed parents having five percent or more apparently receptive silks at the time is disqualified for certification unless adequately isolated from the shedding seed parent.

(c) Sucker tassels and portion of tassels are counted as shedding pollen when two inches or more of the central stem, the side branches, or a combination of the two have the anthers extended from the glumes.

(5) A male sterile seed parent may be used to produce certified hybrid corn seed by either of two methods:

(a) Seed of the normal fertile seed parent is mixed with the seed of the male sterile seed parent of the same pedigree either by blending in the field at harvest or by size at conditioning time. The ratio of male sterile seed parent seed to normal seed parent seed does not exceed two to one.

(b) The male parent involves a certified pollen restoring line or lines so that not less than one-third of the plants grown from the hybrid corn seed produce pollen that appears to be normal in quantity and viability.

(6) Hybrid corn roguing:

(a) Definitely off-type plants in a parent line planted for the production of single cross or three-way cross hybrid corn seed to be used for grain or forage production must be completely destroyed so that suckers do not develop.

(b) Plants showing definite hybrid vigor or a definitely different type from the parent being inspected must be classified as definitely off-type.

(c) An isolation in which more than two-tenths of one percent of definitely off-type plants in the parent or parents have shed pollen, at a time when more than five percent of the seed parent plants have apparently receptive silks, is disqualified for certification.